1. Field of the Invention
The present invention pertains to fiber optic connectors and components of fiber optic connectors. The invention more particularly concerns components used to make an optical connection between two ferrules.
2. Discussion of the Background
Connectors which mate MT style ferrules are known in the art. One such connector 10 is shown in FIG. 1. The connector 10 includes a ferrule 12, a spring 22, alignment pins 14, 18, alignment pin holders 16, 20, and housing halves 24, 26. Each housing half 24, 26 is hermaphroditic. The housing halves 24, 26 retain the ferrule 12, the spring 22, the alignment pins 14, 18, and the alignment pin holders 16, 20. The ferrule 12 conforms to the MT standard. The spring 22 is a coiled, compression spring having closed ends.
When another connector similar to connector 10 is introduced to connector 10, the other connector does not have alignment pins 14, 18 since the ferrule of the other connector has alignment pin receiving holes which accept the alignment pins 14, 18 of connector 10 so as to align the two connectors. Alignment is critical so that optical communication is realized between the optical fibers of the two mating ferrules.
Also, when the two MT style ferrules mate, the mating ends 13 of the ferrules butt up against one another. For continuous optical communication between the two ferrules, the two ferrules must maintain contact with one another. The housing, formed of housing halves 24, 26, contains the spring 22 which contacts the ferrule 12. When connector 10 is mated with the other connector, the ferrule 12 compresses the spring 22 so that a force is transmitted between the mating end 13 of each ferrule so as to keep the mating ends 13 in contact with one another.
When the connector 10 is attached to a fiber optic ribbon cable, the ribbon cable must be thread through the spring 22 before the ferrule 12 is attached to the ribbon cable. FIG. 2 is a perspective view of the assembly of the ferrule 12 to a fiber optic ribbon cable 30. One end of the ribbon cable 30 is pig tailed into an optoelectronic device 36. The other end of the ribbon cable 30 has multiple optical fibers 32 ready for termination to a ferrule. Since the ferrule 12 is larger than the inside diameter of the coiled spring 22, the ribbon cable 30 is thread through the inside diameter of the coiled spring 22, and then the multiple optical fibers 32 of the ribbon cable 30 are terminated with the ferrule 12. Once this procedure is complete, then the alignment pins 14, 18, the alignment pin holders 16, 20, and the housing halves 24, 26 are added so as to complete the termination of the ribbon cable 30.
Some optoelectronic devices are pig tailed and pre-terminated with an MT ferrule. FIG. 3 is a perspective view of such a device. Also, some jumper cables are pre-terminated with each end of the jumper cable being terminated with respective MT ferrules. Optoelectronic devices 36 and jumper cables terminated in such a way can not be used with the components shown in FIG. 1 since the ferrule 12 will not fit through the inside diameter of the coiled spring 22. To salvage such devices, the ribbon cable 30 is cut so as to expose the optical fibers, then the ribbon cable 30 is threaded through the inside diameter of the spring 22, and then the optical fibers of the ribbon cable 30 are terminated to the ferrule 12. The labor involved in such work is expensive.
Another draw back to the connector 10 of FIG. 1 is that in extreme shock, vibration, and thermal environments, the mating ends 13 of two mating ferrules 12 may lose contact with one another. In shock and vibration environments, the mass of the ferrule 12 may be accelerated which generates a force. If the force is great enough, the ferrule 12 will further compress the spring 22 thus causing the ferrule 12 to move away from the other ferrule. Such loss of contact results in a loss of optical communication between the two ferrules. In an extreme thermal environment, the housing halves 24, 26, the ferrule 12, and the spring 22 may grow or shrink relative to one another at various rates due to different values of the respective coefficients of thermal expansion of the materials that make up each of the listed piece parts. If the piece parts grow or shrink too much relative to each other, the spring 22 will lose its compressive load. Once the compressive load is lost, the mating ends 13 of the ferrules 12 will lose contact with each other. If the mating ends 13 of the ferrules 12 lose contact with each other, then the ferrules lose optical communication with one another. The loss of optical communication is not desirable.